There are only so many places I can go when it's raining.
The number of places you can go and things you can do are limited on rainy days.
ーThere are only so many places I can go when it's raining.
「雨の時は行けるところが限られている」
There are only so many ... で「…が限られている」
ーThe number of places you can go and things you can do are limited on rainy days.
「雨の日は行けるところやできることが限られている」
to be limited で「限られている」
ご参考まで！
カナダ 
